Wet room questions!

[SJRSJR]

Apologies for asking what is asked over and over but when I do a search here, the returned posts are so old that I suspect new products will have overtaken them. I've read a lot of them but there seems to be different approaches and I'm getting a bit confused by what's needed for a bathroom. The shower area will be level access/ceramic tile like a wetroom. Size is 3.5m x 2m and is on the first floor.

Floorwise - I've pulled up all my floorboard and I'll be working up from the joists.

NoMorePly straight on the joists has been recommended but believe there's a difference between waterproof and water resistant, and cement based products like NMP, Hardiebacker and Aqua Panel are merely water resistant i.e. water will not change the inherent structure of the material but it can still pass through and saturate what's behind it. That makes me nervous. Whereas I believe Kerdi, Wedi and Marmox are waterproof but they can't go straight on the joists, there'd have to be a substrate.

* If I do use 22mm NoMorePly do I also need to tank? (Assuming I follow the NMP installation instruction as regards taping joints etc)

* If I do need to tank, which is better, a roll/stick-down mat like Impey self adhesive, Ditra/Dural with adhesive or a paint-on one like Mapei?

* As the mat seems to be a decoupling membrane, is that in all circumstances preferable on timber floors?

* If I do need to tank/decouple could I just used a wood substrate and no backerboard? If yes, WBP, OSB or marine ply?

* If backerboards need tanking anyway would an 18mm ply base plus 6mm backerboard be better than 22/25mm ply?

Wall wise - I've got 2 bare internal stud partition and 2 exterior brick cavity walls that have a plaster scratch coat.

For the exterior walls I was thinking of dot and dabbing foam insulated tile backerboard like Marmox where there's going to be water. Should I also tank this with roll-on mat or paint-on tanking?

* For the interior walls, which are away from the bath/shower area can I just tile on to moisture resistant plasterboard?

* Finally, in a bathroom and away from the wet areas is there ever a time where you can just use ordinary plasterboard which can be skimmed and painted?

Sorry for so many questions but thanks in advance for any help.

 

[ChrisNason]

Mine was done with this kit. Just one slope down to a full width drain. Plenty of advice on fitting...

https://wetroommaterials.com/produc...th-linear-drain-against-the-wall/1k-unislope/

 

[jamiesun]

Mate, bathroom prep can be a minefield with all the conflicting advice! You're on the right track though, which is half the battle.

For the floor:
If you're using 22mm NoMorePly with their install guide (glued & screwed, taped joints, etc.), structurally it should be fine, but it’s best to tank the wet areas.
Cement boards like NMP are water-resistant, not waterproof, so tanking gives extra protection.Mapei’s paint-on tanking system is a solid choice—easy to apply and covers all gaps. Ditra/Dural-style mats are great for decoupling timber floors, but not a replacement for tanking.If you go for a mat system, Ditra/Dural can provide both decoupling and waterproofing if installed correctly, so extra tanking may not be needed.For skipping backerboard, you need a solid substrate—WBP ply works best (marine ply is overkill and pricey).
Even with ply, tanking is a must in wetrooms.An 18mm ply base with 6mm backerboard is a good option for added rigidity. Just ensure everything’s well-supported underneath.

For the walls:
Dot & dab insulated tile backerboard on exterior walls for better insulation and a solid tiling surface.
If it’s a wet area, tanking with a roll-on mat or paint-on system adds extra protection.
Moisture-resistant plasterboard is fine for interior walls outside wet areas, but avoid direct water exposure.
Ordinary plasterboard can be used away from wet areas if skimmed and painted, but moisture-resistant is best in a bathroom for long-term durability.

Hope that helps! Let us know what you decide.

 

[SJRSJR]

Thanks ChrisNason, I'll have a look.

jamiesun - thank you for the comprehensive answer, that's really helped.

For the floors I think my ideal will be to use NMP with a decoupling membrane then waterproofer. (I recall Ditramat in a previous property and never had a problem).

For the walls, I'll get the foam insulated backerboard on external ones, roll-on mat in the wet areas, then moisture resistant p/b in the non-wet areas.

Just making a decision is a relief, now on to the pricing of materials! Thanks again

 

[mrrusty]

I detest wet rooms. I occasionally stay with people who have them, and a few years in, no matter how you try to keep all the discolouration and mould at bay, they always seem a bit grubby. Give me a proper shower enclosure so the rest of the room stays dry any day.

 

[SJRSJR]

That's interesting, is that a common thing or slack cleaning? I've only had experience of one wetroom and never had any issues, save for spraying the tiles from time to time to get rid of iron oxide stains. But then I had to do the same in the bathroom.

It was an old airing cupboard and toilet knocked together so it was tiny. A shower tray would have taken up the majority of the floor area and looked odd. It had underfloor heating so maybe that helped, I was thinking about doing the same in this one. But it's food for thought, thanks

 

[mrrusty]

The ones I am thinking of have all-tiled surfaces and no screen, and it just seems to me the almost permanently wet surfaces are just a devil to keep free of soap scums and mould. All the humidity escapes in to the room as well, whereas with a shower cubicle with an extract over the condensation is easier to control. I'm sure with good daily cleaning they can be kept sparkly, but IMHO it's just so much easier to clean down a tray and glass screen. Each to their own.

 

[jamiesun]

Thanks ChrisNason, I'll have a look.

jamiesun - thank you for the comprehensive answer, that's really helped.

For the floors I think my ideal will be to use NMP with a decoupling membrane then waterproofer. (I recall Ditramat in a previous property and never had a problem).

For the walls, I'll get the foam insulated backerboard on external ones, roll-on mat in the wet areas, then moisture resistant p/b in the non-wet areas.

Just making a decision is a relief, now on to the pricing of materials! Thanks again

You're welcome, let us know how you get on.

Are you following any online tutorials at all?

 

[SJRSJR]

I've watched a few - most seem to be brand new dead square bathrooms where pipes and wonky walls don't complicate it! Can you recommended any?

I've been pricing up NoMorePly 22mm and came across Cembloc DryBloc 22mm. Seems to be a similar product but about 20% cheaper - do you know it? Thanks.